Adrenaline dosing basics

What adrenaline is used for (new-starter view)

• Adrenaline (epinephrine) is a powerful drug that supports blood pressure and heart function, and treats severe allergic reactions.
• Common anaesthetic uses: anaphylaxis, cardiac arrest, severe hypotension/bradycardia (selected cases), and as an additive to local anaesthetic (specialist use).
• It is high-risk: small volume errors can cause major harm—always double-check concentration, dose, and route.

Key terms: dose, concentration, and route

• Dose is usually in micrograms (mcg) or milligrams (mg). Remember: 1 mg = 1000 mcg.
• Concentration describes how much drug is in each mL (e.g., 1 mg in 10 mL = 100 mcg/mL).
• Route matters: IM (intramuscular) is standard for anaphylaxis outside arrest; IV is for peri-arrest/arrest and specialist titration with monitoring.
• If unsure: stop, read the ampoule/label, and ask for a second checker.

Common concentrations you will see (and how to interpret them)

• 1:10,000 = 0.1 mg/mL = 100 mcg/mL (often supplied as 1 mg in 10 mL). Commonly used in arrest/peri-arrest settings.
• 1:1,000 = 1 mg/mL (often 1 mg in 1 mL). Commonly used for IM anaphylaxis.
• Avoid relying on ratio language alone (1:1,000 etc.). Prefer mg/mL or mcg/mL and read the label carefully.

Adult anaphylaxis: first-line dosing (typical UK practice)

• First-line: IM adrenaline 500 mcg (0.5 mg) into the anterolateral thigh.
• Using 1 mg/mL (1:1,000): give 0.5 mL IM.
• Repeat IM dose every 5 minutes if there is no improvement or deterioration, while treating airway/breathing/circulation and calling for help.
• Give high-flow oxygen, lie flat with legs raised (unless breathing is worse), and start IV fluids early (e.g., crystalloid boluses).
• IV adrenaline in anaphylaxis should be given only by experienced clinicians with close monitoring; dosing is much smaller and titrated.

Cardiac arrest (adult): standard dosing

• Dose: adrenaline 1 mg IV/IO as per resuscitation guidelines.
• Typically given as 10 mL of 1:10,000 (100 mcg/mL) = 1 mg total.
• Timing depends on rhythm per local/Resus Council guidance; ensure high-quality CPR and early defibrillation when indicated.
• Flush after IV drug delivery and continue CPR immediately.

Peri-arrest / severe hypotension in theatre: cautious IV use

• In anaesthesia, small IV boluses may be used for profound hypotension with bradycardia or vasodilation, but require monitoring and senior support.
• Typical starting bolus range: 10–50 mcg IV, titrated to effect (local policy may vary).
• Practical prep: use a clearly labelled dilute syringe (commonly 100 mcg/mL) so small doses are measurable.
• Reassess cause: depth of anaesthesia, bleeding, anaphylaxis, high spinal, sepsis, tamponade/tension pneumothorax, etc.—treat the underlying problem.
• If repeated boluses are needed, consider an infusion and escalate early.

How to make sense of volumes (worked examples)

• If you have 1:10,000 (100 mcg/mL): 1 mL = 100 mcg; 0.1 mL = 10 mcg; 0.5 mL = 50 mcg; 10 mL = 1 mg.
• If you have 1:1,000 (1 mg/mL): 0.5 mL = 0.5 mg = 500 mcg (adult IM anaphylaxis dose).
• Always write down the target dose first (mcg or mg), then calculate the volume from the concentration.

Safe practice checklist (before you give it)

• Confirm indication and route (IM vs IV vs IO).
• Read the label: concentration (mg/mL), total amount in syringe/ampoule, and expiry.
• Use a second checker for IV adrenaline whenever possible.
• Use a dedicated, clearly labelled syringe; keep it separate from flushes and other clear syringes.
• Monitor: ECG, blood pressure (preferably non-invasive cycling frequently or arterial line if available), SpO2; be ready for arrhythmias and hypertension.
• Document dose, route, time, response, and any adverse effects.